Clamps are used in applications where electrical cables, bundles of wires, tubing, or the like need to be fixedly gripped and attached to a structure or component. Clamps typically have an outer shell, or a clamp shell, which houses a grommet made from an elastomeric material. The object to be clamped is placed within the grommet, which is placed inside the clamp shell where the grommet evenly grips the object. The grommet is made of an elastomeric material and exerts a cushioned gripping force against the gripped object. Grommets have a tendency to move within the clamp shell prior to and during assembly, during service, and during maintenance. The assignee of the present invention currently glues the grommets into the clamp shells, in gas turbine engine applications, because the grommets move radially and axially inside the clamp shells before and after installation.
When clamps are used for gas turbine engines or airframes, the use of glue to attach the grommet to the clamp shell is not practical. The gluing operation is not practical because it requires hours for the glue to cure, or it requires an external heat source to shorten the gluing cure time.
Other clamp designs, such as disclosed in U.S. Pat. No. 4,338,707, have a continuous metal band with a grommet wrapped around the outside band. These clamps, however, do not have a large access area for the tubing to be placed inside the band. To have access to the clamped object, a fastener is detached from the clamp. The loose fastener may be lost during maintenance on the clamp or on the gripped object. If the loose fastener is ingested during engine operation, the potential exists for foreign object damage to the engine.
Another clamp design, shown in U.S. Pat. No. 2,355,742, employs a grommet that requires an elaborate manufacturing process to mate the outer clamp shell to the grommet. The grommet has an isogrid pattern that projects from its outside diameter and mates into a mating groove in the inside diameter of the clamp shell. The manufacturing of the isogrid groove in the clamp shell is a costly process. In addition, when this disclosure is applied to an arcuate clamp, like the present invention, the material removed from the inside of the clamp shell is in a high stress area. If material is removed from the inside of an arcuate clamp shell in a high stress area, more material is needed to thicken the clamp shell to offset bending stresses. The added material results in a thick and heavy clamp shell.